Woody Plants That Spread (Aggressive Trees and Shrubs)

Woody Plants That Spread (Aggressive Trees and Shrubs)

Part of Ep. 703 Invaders

Premiere date: Jul 10, 1999

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
Perennials aren't the only plant that can spread or take over a yard or garden. There are many shrubs and trees that fall into that category, too. We're at Johnson's Nursery in Menomonie Falls. And I'm with the plant propagator, Mike Yanny. Mike, do trees and shrubs spread differently than perennials do?

Mike:
No, Shelley, it's basically the same. They spread by suckering and seeds and layering. Suckering being where the plant will send underground shoots or roots out away from the plant from which shoots will arise. These are called the suckers. And the suckering plant typically will form large colonies. And some of our worst invasive plants are suckering plants.

Shelley:
Then there's the seeders. And those can re-seed almost anywhere.

Mike:
Right, there's a lot of trees and shrubs that grow from seed.

Shelley:
What about this one behind us?

Mike:
This one behind us is an example of a layering plant. This is Stephanandra incisa crispa, a cutleaf stephanandra. This is an excellent plant for quickly filling in an area, like we have here.

Shelley:
Would it have a particular use, where I might appreciate owning this plant?

Mike:
Some people like it for erosion control, where you would have a steep hillside that you wouldn't want to mow because it would be too hazardous. You could put that plant on there. It would quickly fill it in and cover the ground so all your soil wouldn't wash away.

Shelley:
And obviously, it's a full sun plant.

Mike:
It is a full sun plant. But this is also an excellent shade plant.

Shelley:
Oh, really?

Mike:
This is one of the few plants that will flower in full shade.

Shelley:
Wow, then it's really versatile. What about hardiness, then?

Mike:
It's a zone 4 plant.

Shelley:
So, it's going to hang in most of Wisconsin.

Mike:
Yeah.

Shelley:
Can we look at how it spreads, Mike?

Mike:
Sure. I'll show you how it layers. What happens is, these beautiful arching branches come down and touch the ground, like we have here. And then, when they hit the soil, they'll root in and a new plant will form. If we look back in here, we can see, here's a branch, here's a tip that hit the ground. And a small plant is forming from that tip.

Shelley:
So, it's just going to keep spreading outward from these little babies.

Mike:
Right, as these branches go outward, it gradually increases it's area.

Shelley:
Is this going to become a problem in my yard and garden?

Mike:
No, it's not what I would consider an invasive. It spreads nicely.

Shelley:
But we wouldn't plant it as a specimen plant?

Mike:
No. It should be massed.

Shelley:
Give it room to grow.

Mike:
Shelley, I wanted to show you these little tree and shrub seedlings. And here we have a baby Hawthorne, a black cherry and this is a Dogwood.

Shelley:
We're under a hawthorne, so I can kind of guess that the hawthorne seed fell here. Where did the others come from, then?

Mike:
They had to come probably from a bird sitting up in the tree, here.

Shelley:
So, they can really pop up anywhere.

Mike:
Yes.

Shelley:
Is there a great way to use them in my landscape? Or, can they be a problem because they just kind of appear out of nowhere?

Mike:
Well, the black cherry, which came from about a quarter of a mile away, because that's the only one around, can be very useful for a person who would have a large property and who wanted to create a woodland. Say they had an open field and they wanted to create a woodland, they'd plant a few black cherries. They develop seed relatively young in life and then would spread around on their own.

Shelley:
So, you'd get a woodland pretty quickly.

Mike:
Yes.

Shelley:
But it sounds like you said in a large area. In a small area, are these not a good choice?

Mike:
In a small area, they would be a very bad choice because your neighbors would not be happy. They'd be all over their yard.

Shelley:
So, we really need to know the behavior of a plant that re-seeds before planting it in a yard.

Mike:
Right, we have to use our head and be courteous and have some invasive plant etiquette.

Shelley:
Mike talked about invasive plant etiquette. Here's a plant that has no etiquette. Sumac is a real pain in my yard. I'm constantly mowing it out of the lawn. And I didn't plant it in my yard.

Mike:
Well, we have a similar problem here, Shelley. These sumacs that are growing here aren't growing here because I wanted them there. These are coming up from suckers from last year's crop. This crop was dug last fall and we inadvertently left some root pieces in the ground. And so, the shoots are coming up off of these root pieces and we've got more plants here.

Shelley:
And it's just going to keep filling in. There's really no easy way to kill this stuff.

Mike:
Well, you would have to use an herbicide.

Shelley:
If something is this aggressive, why would anyone want to plant it on purpose?

Mike:
Well, it's an excellent plant for mass plantings. And here in Milwaukee County, along the freeway systems, there are beautiful plantings of it. And every fall, people come in and want to buy some for their yard because it's so pretty with its beautiful red color.

Shelley:
I hope then, that that's the case where we're telling people, if you have a small, pocket-sized yard, don't plant sumac. We really need to know what the plant's going to and make sure it has enough room to spread.

Mike:
Exactly. You have to warn them.

Shelley:
Thanks, Mike.

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